Brachyrhamdia marthae

This species grows to 7–8 cm. It has an elongated body, large fins, and a forked tail. Long, thin barbels surround the mouth. Adults are drab, mostly grey and dark. Young specimens are paler and somewhat translucent, giving them a pinkish appearance.

The species inhabits South America, mainly in the Jurua, Mamore, and Madeira river basins. It is a freshwater demersal fish that prefers the bottom. In the wild, water temperature ranges from 24 to 26°C, with a weakly acidic pH of 6.0–7.0.

This species is generally peaceful. However, in a small tank it can show territorial behaviour, competing with its own kind for bottom space. Rivalry is also possible with other bottom-dwelling species. Choose non-aggressive tank mates of similar size that occupy the middle and upper levels. Remember that fry and small fish small enough to fit in the mouth may be eaten.

A group of 3–4 fish needs a tank of at least 120–130 litres. Tank layout should focus on the bottom design. Alternate open substrate areas with sheltered zones. Use natural refuges such as driftwood or artificial decorations. Gravel or rocky substrates are preferred. Lighting should be dimmed, which can be achieved with floating plants for shade. Other decoration is optional or suited to other residents. Brachyrhamdia marthae is undemanding and adapts well to different conditions. It is comfortable at 24–26°C with pH 6.0–7.0 and water hardness up to 15 dGH.

The fish readily eats most aquarium foods. However, it has a weak satiety response, so overfeeding is a risk.

There are no reports of breeding in captivity. Like other members of the genus, this species lives with Corydoras catfish in the wild, mimics their colouration, and is caught alongside them. No external sexual differences are known, and the species is not bred deliberately.

No diseases specific to this species are known. With proper conditions — clean water, a balanced diet, and peaceful tank mates — health problems are usually avoided. Poor conditions are the main cause of illness: they weaken immunity and make the fish susceptible to infections always present in the tank. If you notice lethargy, thinning, loss of appetite, or clamped fins, first check water parameters and ammonia, nitrite, and nitrate levels. Restoring good conditions often leads to recovery. These catfish have naked skin without scales, so they are more sensitive to medication than most aquarium fish. Malachite green and copper-based treatments should be used with caution and at roughly half the package dose.

When selecting fish at the store, look for the following signs: active behaviour with no visible skin damage such as sores, film, or bleeding; clean fins with no signs of rot or white spots; normal behaviour showing no signs of emaciation and active response to stimuli; absence of stress, shown by unnatural colour or prolonged hovering at the surface.